I. Field of the Invention
The present invention is related to vitreous cutters that are used in vitrectomy procedures to remove vitreous from the eye. In particular, the present invention is related to vitreous cutters having a light source to illuminate a portion of the eye.
II. Description of the Related Art
Vitrectomy is a procedure in which the degenerative vitreous is removed to clear the opaque optical media (vitreous) or to eliminate traction on the retina which produces a localized or generalized retinal detachment. The function of a vitrectomy instrument is described in patent U.S. Pat. No. 4,099,529 to Peyman, the entire contents of which are herein incoprporated by reference. That is, generally, the cutting part includes concentric tubing. An inner tube serves as the inner cutting edge of the instrument and has an oscillating action, and the opening in the tightly fit outer tube serves as the outer edge of the cutting. The vitreous is aspirated through a small opening close to the tip of the outer stationary tube, i.e., the outer cutting edge. The aspiration force, generated by a pump, when applied through the inner tube draws the vitreous through the outer hole toward the inside of the inner tube. The oscillation of the inner tube cuts the vitreous/tissue trapped in the opening of the outer tube and is aspirated into a reservoir. To balance the intraocular pressure, physiologic saline solution is infused through a second independent “infusion tube” placed inside the eye cavity through a separate incision in the eye wall.
During the procedure the vitreous cavity is illuminated through a separate fiber optic brought inside the eye through a third incision. The diameter of the vitrectomy cutting cutters varies between 20-23-25-27 gauge. The most desirous sizes are a 23 gauge, 25 gauge and 27 tubes because these sizes eliminate the need to close the incision in the eye wall by a suture and the smaller the instrument is, the less traumatic the surgery becomes.
There are several disadvantages of the conventional systems. First, there is a need for at least three incision for the cutter, infusion and the light sources. Second, the 25 gauge and 27 gauge tips, because of their size are too flexible inside the eye. That is, the slightest pressure that moves the eye during surgery also can bend the shaft of the cutter in one direction at the incision site while the inside portion of the shaft moves in another direction. This movement can be disturbing to an operator who does not expect motion in the opposite direction than which was intended and can cause injury to the fine structure of the lens or the retina. Third, in myopic eyes having a longer axial length than normal, a longer (36-38 mm) than normal shaft (e.g., 30 mm) is required. This makes the instrument flimsy and not desirable.